Sydney Mardi Gras ready to pop the cork

An enormous exploding champagne bottle, giant butterfly puppets and a wedding ceremony with a difference will form some of the key moments in the 2018 Sydney Mardi Gras parade.

Final preparations are underway ahead of Saturday's colourful display, which will celebrate 40 years of Mardi Gras and is expected to attract nearly half a million people along the iconic Oxford Street route.

There will be 12,500 participants on 200 floats, the largest of which will be carrying about 250 people involved in the original 1978 parade and subsequent riot.